This invention relates in general to the field of obstetrics and, more particularly, to an instrument for induction of labor as well as a method for inducing labor.
Methods for induction of labor are divided into two primary categories, namely medical and mechanical. The particular method depends upon the condition or state of the involved organs with respect to delivery. The medical method would be the method of choice when the cervix is in a fully matured, loose condition and the uterus sensibility is heightened, or when the cervical orifice has dilated more than the width of two fingers. Only an intermittent intramuscular injection of posterior pituitary extract or an intravenous drip is adequate, in most cases, to assure a successful delivery. If with such conditions an artificial rupture of the amniotic membrane is effected, a more certain result can be obtained. However, when the cervix has not reached a state of maturity the medical method is not effective. Thus, to practice a medical method the particular organs must have reached a predetermined condition of potential delivery readiness. Without such even increased amounts of medication are insufficient to induce labor. Therefore, the medical method has recognized limitations and can only be used under certain conditions.
The mechanical method is employed when induction of labor is necessary in those situations wherein the particular organs have not reached the level of delivery readiness as would indicate resort to the medical method. Among the more well known mechanical methods are the Bougierung method, being the induction of an instrument for dilating constricted areas; metreurysis, being a dilatation of the uterine cervix with a metreurynter, and colpeurysis, involving a mechanical dilatation of the vagina. However, such methods have not in practice by any means proved infallible and thus the results obtained have been quite uncertain. In many cases resort has necessarily been made to cesarean section in an effort to save the child. It is commonly recognized that when the death rates of the full and frank presentation and the footling presentation are compared, the prognosis for a sound delivery is more unfavorable in the latter presentation. Such prognosis has heretofore led to the view that delivery of footling presentation, whether single or double, should preferably be effected by cesarean section. Despite the stages of development of both types of methods, medical and mechanical, certain types of birth have not proved reliable by either method.
Therefore, it is an object of the present invention to provide an instrument for inducing labor which is useful regardless of the presentation of the fetus thereby being productive of a diminution of the death rate with certain types of births which had been considered particularly hazardous heretofore.
It is another object of the present invention to provide an instrument of the character stated the use of which markedly reduces the heretofore accepted necessity to the resort to cesarean section.
It is a still further object of the present invention to provide an instrument of the character stated which has been extensively tested so that its effectiveness is established.
It is another object of the present invention to provide an instrument of the character stated which may be easily utilized by a practitioner with limited instruction.
It is a still further object of the present invention to provide a method for inducing labor which promotes a most substantial degree of sound deliveries without peril to the fetus despite the manner of presentation of the fetus.
It is a further object of the present invention to provide an instrument for the induction of labor which is not harmful to the mother and thus may be used with safety.
It is another object of the present invention to provide an instrument for the induction of labor which may be most economically manufactured; which is most durable in usage; and the practice of the same has promoted a level of reliability hitherto unknown through the performance of the customary medical and mechanical methods.
The present invention comprehends, in essence, a tubular body as a catheter type having an inflatable balloon or bag fixed on the normally forward or leading end of the catheter and enclosing the adjacent portion of the catheter which is provided with a port or orifice for discharge therethrough of a compatible liquid, such as, sterile saline solution, or even water, into the balloon for inflating same with a predetermined volume of such liquid dependent upon the presentation of the fetus. The instrument is inserted between the uterus wall and the amniotic membrane through the cervical orifice and after such insertion the liquid is gradually fed into the balloon through the catheter portion to a predetermined limit if there is head presentation to avoid the danger of prolapse of the umbilical cord or the possibility of a change of position of the fetus. In the event there is a breech presentation, the amount of liquid introduced into the balloon is in greater amount for purposes presently appearing. At the appropriate juncture the instrument is automatically removed by dropping through the cervical orifice.